How to make the most of three days in DC

It's definitely worth the trip - there is so much to see and do, much of it is free. Be prepared for a lot of walking - it's the best way to see the city. But do take advantage of the metro. It's one of the easiest systems to understand and will get you all over the city relatively quickly: www.wmata.com. There is normally weekend track work so be prepared for some delays if you come over a weekend.

The National Mall and all of its museums are a must. Start on Capitol Hill and 8th Street, NE/Barracks Row. There are great places to grab coffee and breakfast. Walk west down Pennsylvania Ave and you'll run right into the United States Capitol, the US Supreme Court, and the Library of Congress. Keep walking and you'll hit the Mall and the Smithsonian Museums. The National Gallery of Art is a must-see. 

DC is made up of many small, diverse neighborhoods. Check out  H Street if you are up for a lively, party scene. There are some great restaurants and bars on the H Street Corridor. Dupont Circle is beautiful for a walk during the day. Head to Georgetown (Washington DC) if you want high-end shopping. Cleveland Park and upper NW is quiet but has some wonderful restaurants and it's just up the street from the National Zoological Park. 

One of my favorite areas isn't even in DC. Take the metro to King Street and walk towards the water. Old Town Alexandria is a gem. 

Enjoy! 

Absolutely do not miss seeing the Library of Congress. I have lived here for 10 years and it is my favorite tour (better than the White House and less crowded than the Capitol), and many people don't see it when they visit DC. They give free scheduled tours, just look up the website.

I would look into a bus tour, you'll get to see the ENTIRE city and what DC has to offer. I would make this one of the very first things you do when you come to DC, you will see some of the most notable historic sites in our country's history, as well as all of the great monuments. If you're looking for a more educational experience you can always go down to the National Mall (holds the National monument--the Pencil) and all aligned the Mall are National museums and art galleries. If that's not your speed and you're looking for something cool and hip to do, check out the Capitol Skyline Hotel in SW DC, it is located right by Nationals Baseball stadium. Capitol Skyline during the summer has it's rooftop pool opened and its one of the trendiest places to be if you're a young 20 something. There's a nice open bar, dj, and tons of lounges by the pool. 

Absolutely!  Make the most of your three days.  I'd spend one day--if you haven't been before--strolling around and seeing the main monuments (Washington Monument, Lincoln Memorial, Thomas Jefferson Memorial, Martin Luther King, Jr. Memorial, Fdr Memorial, Washington, Arlington National Cemetery). If it's nice, walk! There are also bus and segway tours.  Grab lunch, sit and people watch, etc.  Day 2, hit the museums. Prioritize your 2-3 favorites, including the Smithsonian, so you won't miss out, and go early if you are interested in those that require tickets (United States Holocaust Memorial Museum, National Museum of Crime & Punishment, International Spy Museum, Corcoran Gallery of Art).  Day 3, relax!  Walk around a neighborhood, like Georgetown (Washington DC) or H Street NE; visit some restaurants, enjoy some DC-brewed beer.

All of the national museums are free: National Air and Space Museum, Smithsonian American Art Museum, National Portrait Gallery,  Infinity - American Museum of Natural History, Asian art, Freer Gallery of Art or the Arthur M. Sackler Gallery. There are approx 15 world class options, pick any, you can't go wrong. If I were going to pay for 1 museum, it would be the Newseum. It's approx. $20 and there is nothing else like it in the world. Food? It's all here, but if yr adventurous, DC is home to one of the largest Ethiopian communities outside the country itself. My favorite: Etete on 9th St NW, Yefem tibs, spicy lentils, anything, actually. You can't miss here.  If yr in Penn Quarter and open to Latin food, Jaleo (tapas) is excellent and easy to gauge re. budget, happy hour discounts at the bar. Skip Chinatown, no there, there. French? Bistro d'Oc or Bistrot Du Coin are both budget friendly. Belgian, Brasserie Beck. Want to hang w/ all the people? Busboys and Poets, good drinks, eclectic and inexpensive menu, a few locations.

It honestly depends a lot on what you're interested in seeing! Walking around to everything will take up a good bit of time but it just takes some planning to see everything you want. 

I loved going to the Arlington National Cemetery and seeing everything there including the Kennedy gravesite and the changing of the guards. The Smithsonian National Air And Space Museum is huge and definitely worth seeing. Of course, the Washington Monument, @World War II Memorial and @Lincoln Memorial are must sees (they are right across from each other so easy walking distance). The United States Air Force Memorial was really awesome as well. 

I found that taking the Uber was very beneficial time-wise for me. It's rather cheap and I received discounts for recommending friends and having them use it as well (if you go with a group I suggest doing this - you get a $20 free ride if they use it).

Like others have said, this depends on what exactly interests you. There is so much in DC that is worth the time and is actually free, that you'll have no problem filling three days. Here are my suggestions:

Day 1

The Monument Walk + White House (1/2 day - A lot of walking): The Washington Monument is now open for tours after nearly 3 years of closure for repairs, so book your free tickets ahead if you'd like to go to the top or arrive early in the morning to get them for the same day. The tour lasts just 30 minutes. From here, you can go directly to the World War II Memorial or walk to the The White House. If you go to the White House, then you can easily loop around it, see both sides, stop at either Peet's Coffee & Tea for a beverage or Così for a good lunch, then walk along 17th. Here, you can stop at the Corcoran Gallery of Art and/or the DAR Constitution Hall if you'd like to squeeze in an extra museum, but the walk and seeing the beautiful buildings from the outside is enough given your limited time. Follow this road and you'll run into the World War 2 Memorial. From here, walk along the Lincoln Memorial Reflecting Pool to the Lincoln Memorial. I usually take people to the right from here to see the Vietnam Veterans Memorial (If you want to add two more things on this side, see the Albert Einstein Memorial and the Constitution Gardens which are both small and take no time - just walking time).

From the Vietnam Memorial, loop back to the Korean War Veterans Memorial, then walk to the Martin Luther King, Jr. Memorial, then walk around the Tidal Basin to the Thomas Jefferson Memorial.

Now choose one of the following two 1/2 days to finish your first day.

Holocaust and Engraving (1/2 day): For the second half of your day, either visit the United States Holocaust Memorial Museum and the Bureau of Engraving and Printing. Both require timed tickets in advance, but this is doable. They are both on your way back to the mall from the Tidal Basin.

The National Mall (1/2 Day): There are enough Smithsonians in DC to fill an entire week - or more. Look online and see which 1-2 interest you the most or even pick an exhibit in several and just hop from one museum to the other looking at specific exhibits. You don't have time to see everything in all of them, but they are all fantastic just depending on what interests you. I love the United States Botanic Garden near the US Capital Building and the best museum lunch is at Mitsitam Cafe at the National Museum Of The American Indian which is also a fascinating museum.

Day 2:

The Capital/Library of Congress (1/2 Day): The tours at the United States Capitol are free. Just book ahead online and show up at your time. From here, you can take the tunnel to the Library of Congress which is also free and absolutely gorgeous inside.

From here, either walk to Union Station right next to the National Postal Museum or walk/metro to the Eastern Market which is a nice market (with great pancakes) and a fun area just to walk around and absorb a bit of the local ambiance.

If you have extra time, catch a museum you missed and enjoy the mall.

Other 1/2 days to fill day 3:

Georgetown (Washington DC) (1/2 day - full day): Park and walk. There are great shops and restaurants. You can walk along the Chesapeake & Ohio (C&O) Canal National Historic Park — Georgetown Visitor Center and kayak from the old Jack's Canoes and Kayaks.  If you go to Georgetown, stop for coffee and a handpie at Baked & Wired or try some hand made chocolates at Fleurir Hand Grown Chocolates. If you have time, go up to the Washington National Cathedral.

Arlington (1/2 day): Go to the Arlington National Cemetery and see the Arlington House, The Robert E. Lee Memorial - Museum. It's a beautiful place and has great views of the city. Take a moment to see the Tomb of the Unknowns.

Alexandria (1/2 day): Erin is right. Old Town Alexandria is definitely worth at least a 1/2 day. You can take the metro there and enjoy walking the streets of old town and stopping at one of many amazing restaurants. I love The Pita House for Lebanese food, but there are many great places. Gadsby's Tavern Museum is historical - George Washington ate there. You can tour it and stop for lunch or dinner. The Torpedo Factory Art Center is a fun place if you like art. There's a ton to do and see there - just have fun.

If you love history, take a 1/2 day to see the Mount Vernon Mansion. If you're a fan of Lincoln, take the time to see President Lincoln Cottage which is out of the way, but nice.

If you plan ahead and see at show at Ford's Theatre or see a baseball or hockey game (depending on the season). The Kennedy Center Concert Hall - NSO has free concerts every evening at 6, I think. Just check their website for who's playing.

There are many boat tour options on the Potomac which are nice and you can even take a boat from Washington, DC to Alexandria or even Mt. Vernon or the National Harbor.

Ok... so obviously, you can't do everything in 3 days, but decide what you love and really need to see, and fill in your days accordingly. DC is not a place to relax much unless you're catching a free concert or relaxing in the park - but it's an amazing city. Have fun.

You must see the Smithsonian , the memorials (Lincoln National Memorial, The John F. Kennedy Center for the Performing Arts etc), United States Capitol etc.

Try to go in the spring to see the Cherry Blossoms

United States Holocaust Memorial Museum is an amazing place. Will buy a time ticket. One of the few places you have to pay for in D.C. but well worth it. Kids are moved as well.